1. Field of the Invention
The present invention relates generally to a mounting member and a semiconductor laser apparatus having the same, and, more particularly, to a mounting member provided with a plurality of electrodes and a semiconductor laser apparatus having the same.
2. Description of Related Art
A mounting member provided with a plurality of electrodes has hitherto been known (see, e.g., Japanese Laid-Open Patent Publication No. 2004-55744).
Japanese Laid-Open Patent Publication No. 2004-55744 discloses a semiconductor laser apparatus having three semiconductor laser elements arranged in a predetermined direction and a block (mounting member) provided with three electrodes respectively mounted with the three semiconductor laser elements.
The block is provided with a photodiode (light receiving element) for monitoring an optical output of the semiconductor laser element at a position confronting a rear emission surface (back end surface) of the semiconductor laser element. Therefore, as compared to the case of separately providing a photodiode for monitoring the optical output of the semiconductor laser element, this semiconductor laser apparatus enables a simplified structure and constraint of increase in size.
Each of the electrodes of the block includes an element mounting portion mounted with the semiconductor laser element and a portion (wiring portion) connected to the element mounting portion and bonded with a conductive wire.
The portion bonded with the conductive wire of the center electrode of the three electrodes is formed between the element mounting portion of the center electrode and the element mounting portion of the adjacent electrode on one side. This makes it difficult to arrange the element mounting portion of the center electrode closer to the element mounting portion of the adjacent electrode on one side and hence to arrange the center semiconductor laser element of the three semiconductor laser elements closer to the semiconductor laser element on one side. As a result, it becomes inconveniently difficult to share among the three semiconductor laser elements an optical member such as a lens for receiving light emitted from them.
To improve this inconvenience, a semiconductor laser apparatus has been proposed that includes a portion bonded with a conductive wire of the center electrode projecting in a direction orthogonal to the direction in which the semiconductor laser elements are arranged (see, e.g., Japanese Laid-Open Patent Publication No. 2009-27149).
Japanese Laid-Open Patent Publication No. 2009-27149 discloses a semiconductor laser apparatus having three semiconductor laser elements (laser element portions) arranged in a predetermined direction and a base mounted with the three semiconductor laser elements.
The base is provided with three electrode layers respectively mounted with the three semiconductor laser elements. Each of the electrode layers includes an element mounting portion mounted with the semiconductor laser element and an area (wiring portion) connected to the element mounting portion and bonded with an Au wire. The area bonded with the Au wire of the center electrode layer of the three electrode layers is formed to project from the element mounting portion in the direction opposite to the light emitting surface of the semiconductor laser element.
This semiconductor laser apparatus therefore enables the element mounting portion of the center electrode layer and the element mounting portions of the adjacent electrode layers to be arranged closer and hence enables the three semiconductor laser elements to be arranged closer. This makes it possible to share among the three semiconductor laser elements an optical member such as a lens for receiving light emitted from them.
Japanese Laid-Open Patent Publication No. 2009-27149 is however different from Japanese Laid-Open Patent Publication No. 2004-55744 in that the base is not provided with a light receiving element for monitoring an optical output from the semiconductor laser element (laser element portion). Thus, since Japanese Laid-Open Patent Publication No. 2009-27149 necessitates separately providing the light receiving element to monitor the optical output from the semiconductor laser element, problematically, it is difficult to simplify the structure and the apparatus tends to be large.
It may be conceivable that the photodiode (light receiving element) of Japanese Laid-Open Patent Publication No. 2004-55744 is formed on the base (mounting member) of Japanese Laid-Open Patent Publication No. 2009-27149. Since, however, the area bonded with the Au wire of the center electrode layer must be formed to project from the element mounting portion in the direction opposite to the light emitting surface of the semiconductor laser element (toward the photodiode), the area bonded with the Au wire of the center electrode layer is disposed between the element mounting portion and the photodiode. This results in an increased distance between the element mounting portion and the photodiode, problematically making it difficult to constrain the base from increasing in size.